1. Field of the Invention
The invention relates generally to camera viewfinders, and in particular to an open frame sight viewfinder.
2. Description of the Prior Art
When taking a picture, using a camera, it is necessary to know not only in what direction to aim the camera but also how much of the subject will be included in the picture. For this reason practically every camera has a viewfinder of some kind.
Viewfinders which are built on to or into the camera may be simple framing devices. The frame finder or open frame sight viewfinder is one of the simplest type viewfinders. It often consists of a small peep-sight and a larger frame corresponding to the shape and size of the negative. The larger frame is usually positioned forward of the small peep-sight, and they each have a common viewing axis which extends parallel to the optical axis of the taking lens. When the eye is brought close to the aperture of the peep-sight, the view bounded by the frame is almost exactly the same as seen by the taking lens. The only error is that of parallex, which is more or less negligible for subjects beyond about six feet.
Other frame finders, such as disclosed in U.S. Pat. No. 2,005,366, granted June 18, 1935, are in essence gun sights. In this instance, a small ring-shaped sight is positioned forward of a larger rear sight for viewing the small sight within the viewing aperture defined by the larger sight.
The frame finders, unfortunately, in both of the foregoing examples, do not indicate to the photographer when the camera is incorrectly tilted relative to the subject. As a result, the pictures may not turn out as intended.